Solving Roman Numeral Conversion Questions for the HESI A2

If you are pivoting from studying for the TEAS over to the HESI A2, there is one major math topic you must add to your list immediately: Roman Numerals. While the TEAS retired this topic, Elsevier actively includes 2 to 4 Roman numeral conversions on every HESI exam.

These questions are essentially free points. You do not need to do difficult arithmetic—you just need to decode the letters. Review our Ultimate HESI A2 Study Guide to see how missing these "easy" questions can aggressively drop your composite score.

Step 1: Memorize the 7 Letters

Roman numerals do not use place values (tens, hundreds, etc.) like our Arabic numbers do. They simply add symbols together. There are only 7 symbols in the entire system.

Step 2: The Two Golden Rules

Decoding is easy once you know the two rules of stringing letters together: the Addition rule and the Subtraction rule.

Rule 1: The Addition Rule

If the letters are the same, or if they get smaller as you read Left to Right, you simply add them all together.

• III = 1 + 1 + 1 = 3
• XVI = 10 + 5 + 1 = 16
• CLX = 100 + 50 + 10 = 160

Rule 2: The Subtraction Rule (The HESI Trap)

This is where the HESI will test you. You are never allowed to use four of the same letters in a row. For example, you cannot write 4 as "IIII". You also cannot write 40 as "XXXX".

Instead, if a smaller letter sits directly in front of a larger letter, it means you subtract the smaller one from the larger one.

• IV: I (1) is in front of V (5). Therefore, 5 - 1 = 4.
• IX: I (1) is in front of X (10). Therefore, 10 - 1 = 9.
• XL: X (10) is in front of L (50). Therefore, 50 - 10 = 40.
• XC: X (10) is in front of C (100). Therefore, 100 - 10 = 90.

Check Your Knowledge

Are you ready to box the traps yourself? Take our Free HESI A2 Practice Quiz to drill Roman numeral conversions.

Frequently Asked Questions

Are Roman numerals on the HESI A2 exam?

Yes, Roman numerals are consistently tested on the HESI A2 Math section, unlike the TEAS exam which recently phased them out. You can expect 2 to 4 conversion questions.

What does the Roman numeral 'L' stand for?

The Roman numeral 'L' stands for 50.

How do you write 9 in Roman numerals?

Nine is written as 'IX'. This uses the subtraction rule: because the smaller numeral (I = 1) is placed before the larger numeral (X = 10), you subtract 1 from 10.

Can I write four I's in a row (IIII) for the number 4?

No. A core rule of Roman numerals is that you never repeat a symbol more than three times in a row. Four must be written using the subtraction rule: IV.